Leak sensors using various methods for sensing oil leak are being used. The applicant of the present invention already proposed an oil leak detection device, such as that shown in FIG. 10 of Korean Patent Application No. 10-2009-0065050.
In the oil leak detection device, a conductive line 42 made of a silver compound or pure conductive ink having 0 to 20Ω is printed on a top surface of a base film layer 41 formed of a film, such as PET, PE, PTFE, or PVC in a length direction. A conductive polymer line 43 is attached to the top surface of the base film layer 41 and is spaced apart from the conductive line 42 at a specific interval in parallel to the conductive line 42.
The conductive polymer line 43 reacts to oil, such as hydrocarbone liquid, and detects whether or not oil leak has occurred by sensing a change of a resistance value due to the reaction.
An upper protection film layer 50 is stacked over the base film layer 41. A plurality of holes 51 is formed in the upper protection film layer 50 at specific intervals in a length direction, and the holes 51 are formed at the same location as the location where the conductive polymer line 43 is attached.
Accordingly, when oil flows in through the holes 51 of the upper protection film layer 50, the volume of the conductive polymer line 43 is increased by the porosity of the conductive polymer line 43 and thus a resistance value is increased.
As a result, a controller determines whether or not oil has leaked by reading a change of a resistance value.
However, the conventional oil leak detection device has a high probability that an error can occur because the conductive polymer line 43 for sensing oil leak is very sensitive to a change of temperature.
That is, the conventional oil leak detection device is problematic in that oil leak is erroneously determined because a resistance value is changed due to an increase in the volume of the conductive polymer line 43 although oil leak is not generated when temperature rises due to a change of surrounding environments.